Bucket wheel



GGGGGGG RT GEORG `GEPPERT NNNNNN OR March 28, 1961 G. GEPPERT 2,977,091

BUCKET WHEEL Filed Aug. 19, 1957 Y 7 Sheets-Sheet 2 GEDRG GE PPE RT INVENTOR BJ Pavan ATTORN EYS March 28, 1961 G. GEPPERT 2,977,091

BUCKET WHEEL Filed Aug. 1.9, 1957 7 Sheets-Sheet 3 GEORG GEPPERT INVENTOR ATTORNEY G. GEPPERT BUCKET WHEEL March 28, 1961 7 Sheets-Sheet 4 Filed Aug. 19, 1957 GEORG GEPPERT ATTORNEYS March 28, 1961 Filed Aug. 19. 1957 GEORG GEPPER T March 28, 1961 G. GEPPERT 2,977,091

BUCKET WHEEL Filed Aug. 19, 1957 7 Sheets-Sheet 6 GEORG GE PPERT INVENTOR WM, X144 faul ATTO R N EYS March 28, 1961 G, GEPPERT 2,977,091

BUCKET WHEEL Filed Aug. 19, 1957 i fr sheets-sheet v Fig.13

GEORG GEPPE RT INVENTOR WMI M ATTORN EYB nited States Patent@ BUCKET WHEEL Georg Geppert, Innsbruck, Austria, a'ssignor to Technicax TheA invention relates to a bucket wheel with open buckets disposed at the periphery of a carrier disc and alternately directed toward each side of the wheel. v

When applied to a free jet turbine it is the object of the invention that the bucket wheel should support the bending moment of the buckets, which is givenby the product of the jet pressure with the distance from the jet centre to the bucket foot or root or to the xing point of the bucket, hence sparing the hitherto customarily used stiifenings, strengthenings, ribs and other safety devices.

4A further object of the invention is to provide an impeller for .free jet turbines with as high a specic rate of revolutions as possible.

Moreover, another object of the invention is to providev a bucket wheel for free jet turbines, the buckets of which can easily be manufactured of sheet metal by pressing method. K Y

Also when applied to a reaction turbine or to a centrifugal pump the bucket Wheel of the invention is intended ,to support the bending moment produced by the hydraulic `forces impacting on the buckets.

It is also intended to avoid to a large extent oscillations being originated, which are likely to be the cause of fractures.

The invention essentially consists in a bucket wheel with open buckets disposed on a carrier disc and alternately directed toward each side of the wheel, the inner limiting edge of each bucket being connected to the back of the following bucket.

This step supplies an important improvement in technical stability compared with the known constructions. The bending moment created .by the jet pressure on the buckets in relation to the fastening point on the wheel is supported by the following and preceding bucket.

'The advantages in technical stability are particularly great if the connection of the buckets is continuous from the inlet peripheral knife-edge up to the carrier disc and if the welded joints of the connection kare in a zone free from any bending.

The invention is illustrated in more detail in the drawings, wherein Figure 1 is a view in radial direction of one embodiment of a bucket wheel in accordance with the invention Figure 2 is a View in `axial direction o-f the same ernbodiment Figure 3 is a paraxial section Figure 4 is a top view of a bucket Wheel according to Figures 1 to 3 applied as a carrier disc to a free jet turbine, the casing partially cut open Figure 5 is a view Ain radial direction of Ianother embodiment of a bucket wheel Figure 6 is a view in axial direction and 4Figure 7 is a paraxial section of same embodiment Figure 8 is a side view with casing cut open of the bucket wheel according to Figures 5 to 7 used as a carrier disc fora reaction turbine Y Figure 9 is a view in-radial direction of'a third embodiment ofV a bucket wheel l Patented Mar. 2S, 19,61`

i bucket wheel used as a carrier disc for a centrifugal pump.

` face of the carrier disc 1.

In the bucket wheel shown in Figures 1 to 3, there are provided open single-hollow buckets alternately directed toward each side of the wheel on the double-cone shaped carrier disc y The inner limiting edge 2 of each bucket lies on the rear 3 of the following bucket over its whole length.

The outer @limiting edge 4 runs into the conical surface of the carrier disc 1. yThe angle a between the tangent line ofthe outer *lmit-ing edge 4 at the point of intersection with the conical surface and the cone generatrix passing through the same point is, according to Figure 3, less than a right angle. `The bucket surfaces lare preferably so constructed that at their central inner portion 5 they pass as smoothly as possible into the conical sur-A As can be seen particularly `from FiguresZ and 3, the peripheral knife-edges 6 of all the buckets lie on a cylindrical surface coaxial with the wheel axle 7. As the knife-edges 6 of the bucket wheel lie at lthe outermost periphery, they are easily accessible and can be renewed in the simplest way by means of built-up weldingY and grinding.

As can be seen from Figures l to 3, only the bucket inner parts 14 have a peripheral knife-edge 6. The bucket outer parts 15 are slopedv outwardly at Itheir periphery. With inner part 14 there is meant the portion of the bucket extending from the inner limiting edge 2 of the each bucket to the inner limiting edge 2 ofthe preceding bucket. The outer part 15 is the remaining portion of the bucket.

The inner surfaces i.e. the hydraulic elective surfaces of the bucket have their strongest curvature at the outer parts 15. The inner parts 14 are but slightly inclined to the central plane of the carrier disc 1 normally lying on the wheel axle 7. Consequently, the peripheral knifeedges 6 form a [far displaying zigzag line. i

The extension of the bucket inner parts 14 is in circumferential direction greater than that of the outer parts The bucket wheel according to Figures 1 to 3is able to be used as a carrier disc for a free jet turbine. As such, the bucket wheel is mounted in the usual way in a casing 8 as visible in Figure 4. The water free jet impulsing the bucket wheel flows from a nozzle 9 carried through the casing wall in direction of arrow 10. Arrows 11 indicate the free jet width. This width is substantially of the same size as the axial breadth of the peripheral knife-edge 6. According to Figure 4, the free jet impacts upon the lower half of the bucket wheel; under this admission the bucket wheel revolves in direction of arrow 12.

After impacting upon the buckets or the peripheral knife-edge 6 the free jet separates into branch jets.

The branch jet flowing between the peripheral knifeedges 6 of two neighboring buckets is deliected by the single-hollow shaped bucket, whereby it exerts a hydraulic force upon the bucket and is discharged with as much energy so as not to cause an exit loss of energy beyond the tolerable value, in the absolute exit direction of the arrows 13, along the outer limiting .edge 4 of the bucket acting as outlet edge..

The resultant of the hydraulic forces acts approximately at the centre of the bucket which is just the place where the bucket is supported by the preceding bucket over the entire radial extent from the inlet knife-edge `(ik down tothe periphery of the carrier disc 1'. Through this mutual connection of all buckets alternating toward can be selected, and the bucket ring or wreath can be welded directly to the axle collar, so that space and freedom are gained for a most propitious construction of the buckets in accordance with ilow techniques in order. to attain a high specic rate of revolutions and to make available a high efliciency. Y

The welded joints connecting the buckets to one another along their inner limiting edges 2 (Figures l to 3) lie within zones free from bending, so they are not subjected to undesired strain.

The small diameter of the carrier disc 1, its moderate axial dimension and the simple connection offer little resistance to the branchV iets flowing left and right and also permit an increase of the specific rate of revolutions. This makes it possible to employ free jet turbines where hitherto it was necessary to use Francis turbines.

Due to the special arrangement of the buckets on the carrier disc 1, in particular when the bucket surface at its central inner portion passes smoothly into the conical surface, further advantages are obtained of a fluiddynamic character. Thus parts of the carrier disc 1 contribute to the water dellection. In this manner, the carrier disc 1 adds to its own function another supplementary function according to fluid dynamics.

The selection of the angle a at 90 (Figure 3) and less has in connection with the other measures relating to fluid dynamics and stability a practical significance in accordance with fluid dynamics, whereby simultaneously economy of material is obtained as compared with former constructions of said bucket parts.

According to Figure 4, the water is conducted, in the usual manner, as a cylindrical free jet on to the bucket wheel. The water supply maybe in the form of multiple free jets or the so-called annular jet.

The embodiment of the bucket wheel of the invention shown in Figures 5 to 7 truly differs in its exterior appearance from the embodiment of Figures l to 3 but the features which characterize Athe invention are also present here. The inner edges 2 of the buckets alternating with their open side toward each side of the wheel are adjacent to the back 3 of the following bucket, whereby the supporting line extends fromy the border of the peripheral edge 6 in a curve up to the periphery of the double-cone shaped carrier dsc`1.

Contrasting with the embodiment of Figures l to 3, the buckets here are positioned close to one another. The extension along the circumference of the carrier disc 1 is greater by the bucket outer parts 15 than by the inner parts. The outer limiting edge 4 of each bucket lies with the inner limiting edge of the subsequent bucket in about the same plane comprising the wheel axle. Further, the outer part 15 of each bucket forms with the inner part 14 of the subsequent bucket pairing surfaces slightly converging. The least distance betweeen the outer part 15 of a bucket and the inner part 14 of the following bucket is to be found in the zone of the outer limiting edge 4. The peripheral knife-edges 6 of the bucket inner parts 14 form a compact zigzag line. Further, the bucket outer parts 15 also are ending in peripheral knife-edges which lie in a common coaxial cylindrical surface with the knife-edges 6 of the inner parts 14.

.Y This bucket wheel embodiment is particularly suitable for reaction turbines as can be seen from Figure 8.

The bucket wheel is mounted in a casing 16 and provided with two discharges 17, 18. The water supply is conducted onto the bucket wheel over a spiral casing 19 in direction of arrow 20.`

Owing to the oblique position of the peripheral knifeedges 6 over the bucket partition, the water streaming in direction of the arrows 20 will divide with less shock and the longitudinal oscillation of the impacting water in the pipe is not so easily amplified.V The water leaves the bucket on both sides of the bucket wheel without energy in the absolute direction 21. The direction of the bucket rotation effected thereby is indicated by the arrow 22.

In applying the bucket wheel of the invention according to the embodiment ofV Figures 5 to 7, the result is that the reaction turbine' will somewhat resemble the Francis twin-turbine, only substantially simplified in that owing to the connection of the buckets to one another and to.

the carrier disc 1 the hydraulic and centrifugal forces can be transmitted by the buckets only to the impeller, so that the usual base and bucket wreath of Francis wheels are here superfluous.

Another embodiment of a bucket wheel in accord-ance with the invention is shown in Figures 9 to l1. The difference from the embodiment of Figures 5 to 7 lies in the radial prolongation 23 of the bucket surfaces. This radial prolongation 23 has a breadth of the same lsize as the breadth of the peripheral knife-edges 6 of the'bucket wheel according to Figures 5 to 7.

Figure 12 shows a bucket Wheel according'to Figures 9 to ll as used for a reaction turbine. Like in Figure 8 the bucket wheel is mounted in a casing 16 land is provided with two discharges 17, 18. In the same manner, the water supply is conducted onto the bucket wheel over a spiral casing 19 in direction of arrow 20. Said spiral casing 19 is connected to the casing 16 over a circular area defined by ring-shaped walls 24. The radial prolongations 23 of the bucket wheel are extending in said circular area. This measure secures a reliable hydraulic guidance ofthe streaming water. The arrow 21 shows the direction of discharge of the water discharging without energy. Arrow 22 indicates the direction of rotation of the wheel.

The embodiment according to Figures 9 to 11 is also advantageously suitable for pumps for the delivery of water or air. As shown in Figure `13 the direction of rotation of the wheel and the stream direction are merely reversed. The arrow 25 indicates the direction of rotation of the wheel. The medium to be delivered is supplied in `axial direction of the arrows -26 and discharged radially in the direction of the arrows A27 with increased pressure into the spiral casing 19 here acting as a diffuser.

Having thus fully described the invention, what vI claim as new and desire to secure by Letters Patent is:

l. A bucket wheel comprising a carrier disc, open buckets having substantially the same Wall thickness throughout disposed in staggered arrangement at the periphery of said carrier disc and alternately directed to the right and left with respect to the middle plane of said carrier disc normal to the wheel axle, each bucket being in immediate connection with the back of the following one, the connection of each bucket to the back of the following bucket substantially extending along the entire radial length of said back.

2. A bucket wheel as set forth in claim 1 wherein each bucket is uninterruptedly connected with the neighboring bucket.

3. A bucket wheel as set forth in claim l, wherein the interior angle of the bucket surface between the outer limiting edge of the bucketsand the generatrices of the carrier disc are or less.

4. A bucket'wheel comprising ia carrier disc, openv .ture of the bucket inner surfaces being at the outer parts of the buckets, the inner parts of said buckets being but slightly inclined towards said middleV plane, the bucket inner parts having peripheral edges whereasV the bucket outer parts are sloped outwardly.

5. A bucket wheel comprising a carrier disc, open buckets having substantially the same wall thickness throughout disposed in staggered arrangement at the periphery of said carrier disc and alternately directed to the right and left with respect to the middle plane of said carrier disc normal to the wheel axle, each bucket being in immediate connection with the back of the following one, the region of strongest curvature of the bucket inner surfaces being at the inner parts of the buckets, the outer part of one bucket forming with the inner part of the neighboring bucket pairing surfaces slightly converging, the bucket inner parts las well as the bucket outer parts having peripheral edges lying in `a common cylindrical surface coaxial with the wheel axle.

6. A bucket wheel comprising a carrier disc, open buckets having substantially the same wall thickness throughout disposed in staggered arrangement at the periphery of said carrier disc and alternately directed t'o the right and left with respect to the middle plane of said carrier disc normal to the wheel axle, each bucket being in immediate connection with the back of the following one, the region of strongest curvature of the bucket inner surfaces being at the inner parts of the bucket, the outer part of one bucket forming with the inner part of the neighboring bucket pairing surfaces slightly converging, the bucket inner parts having radial prolongations with peripheral edges which lie in a cylindrical surface coaxial with the wheel axle.

y References Cited in the file of this patent UNITED STATES PATENTS 391,523 Englebright Oct. 23, 1888 417,865 Green Dec. 24, 1889 469,959 Brookwalter Mar. 1, 1892 503,015 Teed Aug. 8, 1893 I534,772 Tutthill Feb. 26, 1895 589,350 Holzhauser Aug. 3l, 1897 607,246 Johnson July 12, 1898 655,271 Pfeiffer Aug. 7, A1900 827,165 Mariner July 3l, l1906 FOREIGN PATENTS 148,973 Australia June 7, 1951 667,129 Great Britain Feb. 27, @1952 678,742 Great Britain Sept. 10, 1952 

